timing chains

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ya i had a question about timing chains jumping. im not talking about little cars where its a belt. i mean big motors where its actually a chain. is it bad when the chain jumps and u have to get a new one? my dad had a 454 where that happend and the motor didnt last much longer after that.
 
Well the timing chain (or belt), also known as the cam chain/belt, controls the relationship between the movement of the crankshaft (and pistons), and the camshaft(s) and valves.

If the cam and crank get out of step, there could be a rather catastrophic meeting between valves and pistons. And as your Dad found out with his 454, that's about it.
 
The timing chain should be replaced as a matter of routine. For cam belts, it's usually between 45,000 and 60,000 miles.

As long as your 454 has have its chain replaced at the prescribed intervals, you're fine. If it's had its chain replaced because it's thrown the chain, I would walk away, yes.
 
well i know this. if theyre a rubber belt you do have to change them every so often. but on the big motors they usually dont have to be changed unless they jumped.
 
It depends on whether the engine is an interference motor or not. Smaller displacement engines tend to be interference engines, meaning that the valves and pistons can collide if they are not coordinated properly by the timing belt/chain. Older, larger-displacement engines may or may not be interference engines, so in many cases it is perfectly possible for the timing chain to break or jump without causing internal damage.

You can't generically say it is or is not a problem. You'll have to find a forum that deals with the type of car involved and find out if it is interference-type or not.
 
I second dukes advice. You have to talk to someone who knows this specific engine.

I had a friend that had an opel with a 1.6 where the cambelt jumped, and got destroyed. Although the engine took no damage from it, he just replaced it and the engine at least seemed to be as healthy as before. He drove a few years with it after that incident without problems.
 

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